The present invention relates in general to an automatic power transmitting system for an automotive vehicle, and more particularly to improvements in such an automatic power transmitting system which incorporates a constant-mesh transmission with synchromesh devices for a plurality of gear positions, and which assures an enhanced shifting feel of the transmission.
As an automatic power transmitting system for use in a motor vehicle, there is known a system which uses a constant-mesh transmission having synchromesh devices that are operated by a suitable actuator device, to selectively establish one of a plurality of gear or speed positions. A vehicle equipped with this type of automatic power transmitting system has a fuel economy comparable to that equipped with a manually operated transmission.
When the constant-mesh transmission of the above power transmitting system is automatically shifted, a clutch disposed between the engine of the vehicle and the input shaft of the constant-mesh transmission must be disengaged before the appropriate synchromesh device of the transmission is operated by the actuator device to establish the appropriate gear position, that is, after the engine output has been temporarily reduced to a suitable level by reducing the throttle valve opening. Further, the clutch must be re-engaged after the synchromesh device has been operated into position for establishing the gear position. Therefore, the shifting operation of the constant-mesh transmission requires a relatively long time during which the clutch is placed in the disengaged state, i.e., during which the transmission is disconnected from the engine. This relatively long time of disengagement of the clutch gives the vehicle driver a poor feel of shifting of the transmission. For minimizing the time of disengagement of the clutch, the transmitting system must require a controller which is capable of achieving a complicated and sophisticated timing control of the engaging and disengaging actions of the clutch.